Three-term U.S. Senator Tom Carper successfully fought off a challenge from community activist Kerri Evelyn Harris in Delaware in Thursday's Democratic primary, after spending several million dollars compared to less than $70,000 by his opponent.
With nearly all of the votes counted, Carper was leading with about 65 percent of the vote, while Harris had about 35 percent, according to state figures.
Carper, 71, was challenged by Harris, 38, who was vying to become the first black woman and openly gay person elected by the state's voters.
The senator is likely to win a fourth term, and faced only token opposition in Senate nominating contests in the past. But Harris drew strong support from outside groups, including Alexandria Ocasio-Cortez, who defeated incumbent Congressman Joe Crowley in a New York City nominating contest in June, and rallied for Harris.
The race was the latest test of whether voters dissatisfied with Democratic leadership would push out an incumbent in favor of a younger, more diverse candidate they see as a potentially more robust opposition to Republican President Donald Trump.